Fix elevated teardown.

[danuker]

On some systems (found on Ubuntu 18.04), compat creates a temporary folder as a superuser ("test user"), but at teardown tries to delete it as the "developer user" (with no permissions).

Here is a failure on a Ubuntu 18.04.4 VM in KVM:

dan@dan-Standard-PC-Q35-ICH9-2009:/share/server$ ./brink.sh test_loop 10 elevated.functional -vx
---> pavement.test_loop
---> pavement.build
::group::Paver build
Cleaning orphaned files in /share/server/build-server
Cleaning orphaned files in chevah/server
cd /share/server/build-server
Skipping current directory
Listing /share/server/build-server ...
Listing /share/server/build-server/lib/python27.zip ...
Can't list /share/server/build-server/lib/python27.zip
Listing /share/server/build-server/lib/python2.7 ...
Listing /share/server/build-server/lib/python2.7/plat-linux2 ...
Listing /share/server/build-server/lib/python2.7/lib-tk ...
Listing /share/server/build-server/lib/python2.7/lib-old ...
Can't list /share/server/build-server/lib/python2.7/lib-old
Listing /share/server/build-server/lib/python2.7/lib-dynload ...
Listing /share/server/build-server/lib/python2.7/site-packages ...
Listing /share/server/build-server/lib/python2.7/site-packages/cffi-1.14.5-py2.7-linux-x86_64.egg ...
cd /share/server
---> brink.pavement_commons.coverage_prepare
::endgroup::
--------------------------------------------------
| Running 0
--------------------------------------------------
---> brink.pavement_commons.test_python
---> brink.pavement_commons.test_super
cd /share/server/build-server
sudo CODECOV_TOKEN=*** bin/python bin/nose_runner.py dan chevah.server.tests.elevated.functional -vx
test_change_folder - elevated.functional.test_ftp_commands:TestControlChannelFTP.test_change_folder ... ok
test_create_delete_folder - elevated.functional.test_ftp_commands:TestControlChannelFTP.test_create_delete_folder ... ok
test_create_folder_over_file - elevated.functional.test_ftp_commands:TestControlChannelFTP.test_create_folder_over_file ... ok
test_delete_file - elevated.functional.test_ftp_commands:TestControlChannelFTP.test_delete_file ... ok
test_delete_file_non_existent - elevated.functional.test_ftp_commands:TestControlChannelFTP.test_delete_file_non_existent ... ok
test_delete_folder_non_existent - elevated.functional.test_ftp_commands:TestControlChannelFTP.test_delete_folder_non_existent ... ok
test_get_current_working_folder - elevated.functional.test_ftp_commands:TestControlChannelFTP.test_get_current_working_folder ... ok
test_get_file_size - elevated.functional.test_ftp_commands:TestControlChannelFTP.test_get_file_size ... ok
test_get_modified_date - elevated.functional.test_ftp_commands:TestControlChannelFTP.test_get_modified_date ... ok
test_get_modified_date_non_existent - elevated.functional.test_ftp_commands:TestControlChannelFTP.test_get_modified_date_non_existent ... ok
test_rename_empty_destination - elevated.functional.test_ftp_commands:TestControlChannelFTP.test_rename_empty_destination ... ok
test_rename_empty_source - elevated.functional.test_ftp_commands:TestControlChannelFTP.test_rename_empty_source ... ok
test_rename_file - elevated.functional.test_ftp_commands:TestControlChannelFTP.test_rename_file ... ok
test_rename_folder - elevated.functional.test_ftp_commands:TestControlChannelFTP.test_rename_folder ... ok
test_rename_non_existent - elevated.functional.test_ftp_commands:TestControlChannelFTP.test_rename_non_existent ... ok
test_rename_only_spaces_destination - elevated.functional.test_ftp_commands:TestControlChannelFTP.test_rename_only_spaces_destination ... ok
test_rename_only_spaces_source - elevated.functional.test_ftp_commands:TestControlChannelFTP.test_rename_only_spaces_source ... ok
test_change_folder - elevated.functional.test_ftp_commands:TestControlChannelFTPS.test_change_folder ... ERROR
ERROR

======================================================================
ERROR: test_change_folder - elevated.functional.test_ftp_commands:TestControlChannelFTPS.test_change_folder
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/share/server/chevah/server/testing/functional.py", line 147, in setUp
    self.startService()
  File "/share/server/chevah/server/testing/functional.py", line 408, in startService
    message="start the service",
  File "/share/server/chevah/server/testing/functional.py", line 435, in _waitWithTimeout
    self._events_queue,
AssertionError: Failed to start the service as quick as it should in 15 seconds.
deque([Event:0x7fe2fac7d550:20033
a-{"peer": {"protocol": "TCP", "port": 0, "family": "IPv4", "address": "0.0.0.0"}, "uuid": "Process", "name": "Process"}

{"reason": "No reason.", "details": "Traceback: <class 'chevah.server.commons.exception.ServerError'>: <ServerError instance at 0x7fe2faaeffa0 with str error:\n Traceback (most recent call last):\n  File \"/share/server/build-server/lib/python2.7/site-packages/twisted/python/reflect.py\", line 448, in safe_str\n    return str(o)\n  File \"/share/server/chevah/server/commons/exception.py\", line 65, in __str__\n    return self.__repr__()\n  File \"/share/server/chevah/server/commons/exception.py\", line 62, in __repr__\n    self._repr, ''.join(traceback.format_stack())))\nRuntimeError: Use _repr if you need debug serialization.\n20032\n{'details': u\"[('SSL routines', 'SSL_CTX_set_session_id_context', 'ssl session id context too long')]\", 'cert': u'test_data/pki/server-cert-and-key-2048.pem', 'ca': None, 'key': u'', 'crl': ()}\n  File \"/share/server/build-server/lib/python2.7/threading.py\", line 774, in __bootstrap\n    self.__bootstrap_inner()\n  File \"/share/server/build-server/lib/python2.7/threading.py\", line 801, in __bootstrap_inner\n    self.run()\n  File \"/share/server/build-server/lib/python2.7/threading.py\", line 754, in run\n    self.__target(*self.__args, **self.__kwargs)\n  File \"/share/server/chevah/server/testing/threaded_reactor.py\", line 29, in reactor_run\n    _reactor.run(installSignalHandlers=False)\n  File \"/share/server/build-server/lib/python2.7/site-packages/twisted/internet/base.py\", line 1283, in run\n    self.mainLoop()\n  File \"/share/server/build-server/lib/python2.7/site-packages/twisted/internet/base.py\", line 1292, in mainLoop\n    self.runUntilCurrent()\n  File \"/share/server/build-server/lib/python2.7/site-packages/twisted/internet/base.py\", line 888, in runUntilCurrent\n    log.err()\n  File \"/share/server/build-server/lib/python2.7/site-packages/twisted/python/log.py\", line 134, in err\n    msg(failure=_stuff, why=_why, isError=1, **kw)\n  File \"/share/server/build-server/lib/python2.7/site-packages/twisted/python/threadable.py\", line 53, in sync\n    return function(self, *args, **kwargs)\n  File \"/share/server/build-server/lib/python2.7/site-packages/twisted/python/log.py\", line 286, in msg\n    _publishNew(self._publishPublisher, actualEventDict, textFromEventDict)\n  File \"/share/server/build-server/lib/python2.7/site-packages/twisted/logger/_legacy.py\", line 154, in publishToNewObserver\n    observer(eventDict)\n  File \"/share/server/build-server/lib/python2.7/site-packages/twisted/logger/_observer.py\", line 131, in __call__\n    observer(event)\n  File \"/share/server/build-server/lib/python2.7/site-packages/twisted/logger/_legacy.py\", line 93, in __call__\n    self.legacyObserver(event)\n  File \"/share/server/chevah/server/side_effects.py\", line 105, in _handle_twisted_log\n    details = force_unicode(failure.getBriefTraceback())\n  File \"/share/server/build-server/lib/python2.7/site-packages/twisted/python/failure.py\", line 659, in getBriefTraceback\n    self.printBriefTraceback(file=io)\n  File \"/share/server/build-server/lib/python2.7/site-packages/twisted/python/failure.py\", line 744, in printBriefTraceback\n    self.printTraceback(file, elideFrameworkCode, detail='brief')\n  File \"/share/server/build-server/lib/python2.7/site-packages/twisted/python/failure.py\", line 712, in printTraceback\n    reflect.safe_str(self.value)))\n  File \"/share/server/build-server/lib/python2.7/site-packages/twisted/python/reflect.py\", line 448, in safe_str\n    return str(o)\n  File \"/share/server/chevah/server/commons/exception.py\", line 65, in __str__\n    return self.__repr__()\n  File \"/share/server/chevah/server/commons/exception.py\", line 62, in __repr__\n    self._repr, ''.join(traceback.format_stack())))\n\n>\n/share/server/build-server/lib/python2.7/threading.py:754:run\n/share/server/chevah/server/testing/threaded_reactor.py:29:reactor_run\n/share/server/build-server/lib/python2.7/site-packages/twisted/internet/base.py:1283:run\n/share/server/build-server/lib/python2.7/site-packages/twisted/internet/base.py:1292:mainLoop\n--- <exception caught here> ---\n/share/server/build-server/lib/python2.7/site-packages/twisted/internet/base.py:886:runUntilCurrent\n/share/server/chevah/server/testing/functional.py:401:start_listening_from_thread\n/share/server/build-server/lib/python2.7/site-packages/twisted/internet/posixbase.py:495:listenTCP\n/share/server/build-server/lib/python2.7/site-packages/twisted/internet/tcp.py:1406:startListening\n/share/server/build-server/lib/python2.7/site-packages/twisted/internet/protocol.py:77:doStart\n/share/server/chevah/server/commons/factory.py:207:startFactory\n/share/server/chevah/server/commons/ssl.py:1135:_configureSSL\n/share/server/chevah/server/commons/ssl.py:351:__init__\n", "avatar": {"peer": {"protocol": "TCP", "port": 0, "family": "IPv4", "address": "0.0.0.0"}, "uuid": "Process", "name": "Process"}}

c-{"type": "process-component", "name": "Process", "uuid": "Process"})])

======================================================================
ERROR: test suite for <module 'chevah.server.tests.elevated.functional' from '/share/server/chevah/server/tests/elevated/functional/__init__.py'>
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/share/server/build-server/lib/python2.7/site-packages/nose/suite.py", line 227, in run
    self.tearDown()
  File "/share/server/build-server/lib/python2.7/site-packages/nose/suite.py", line 356, in tearDown
    self.teardownContext(ancestor)
  File "/share/server/build-server/lib/python2.7/site-packages/nose/suite.py", line 376, in teardownContext
    try_run(context, names)
  File "/share/server/build-server/lib/python2.7/site-packages/nose/util.py", line 507, in try_run
    return func()
  File "/share/server/chevah/server/tests/__init__.py", line 78, in teardown_package
    mk.fs.checkCleanTemporaryFolders()
  File "/share/server/build-server/lib/python2.7/site-packages/chevah/compat/testing/filesystem.py", line 58, in checkCleanTemporaryFolders
    self.deleteFolder(temp, recursive=True)
  File "/share/server/build-server/lib/python2.7/site-packages/chevah/compat/unix_filesystem.py", line 226, in deleteFolder
    return self._rmtree(path_encoded)
  File "/share/server/build-server/lib/python2.7/site-packages/chevah/compat/posix_filesystem.py", line 440, in _rmtree
    shutil.rmtree(path, ignore_errors=False, onerror=on_error)
  File "/share/server/build-server/lib/python2.7/shutil.py", line 279, in rmtree
    onerror(os.rmdir, path, sys.exc_info())
  File "/share/server/build-server/lib/python2.7/shutil.py", line 277, in rmtree
    os.rmdir(path)
OSError: [Errno 1] Operation not permitted: '/tmp/f90d036c-b855-4113-887a-7b1aca3ab1f0-Cp\xc8\x9b'

----------------------------------------------------------------------
Ran 18 tests in 21.999s

FAILED (errors=2)
Max RSS: 133028
Exit code is: 1
cd /share/server